1. Field of the Inventions
The present inventions relate to power transmitting apparatuses for switching between 2-wheel and 4-wheel modes and locking and unlocking differential devices.
2. Description of the Related Art
Four-wheel buggies, also known as “ATVs” (All Terrain Vehicles), usually include power transmitting apparatuses for connecting and disconnecting power from an engine to the front wheels, which are not-driven wheels, and also switching between 2-wheel and 4-wheel drive modes. Such a vehicle is disclosed in Japanese Laid-open Patent Publication No. 191768/2003.
Generally, the power transmitting apparatus is provided with a differential means (differential gear set) to provide smooth turning of vehicle by absorbing the difference of rotation between left and right wheels. Japanese Laid-open Patent Publication No. 509409/1994 discloses another type of differential system that does not a differential gear set.
Some known designs can limit the differential action of one wheel by incorporating a power transmitting apparatus provided with means for locking the differential means (differential-locking means) in order to prevent a reduction of driving torque under circumstances in which one of left and right wheels of vehicle would be mired in a slippery road such as mud. A more recently proposed design of a power transmitting apparatus include a motor for connecting and disconnecting the driving force and locking and unlocking of a differential means.
For example, one prior art power transmitting apparatus includes an electric motor arranged in either of the left or right sides of a case forming a box of the power transmitting apparatus. The connection and disconnection between an input shaft connected to an engine and an output shaft connected to a front wheel as well as the locking and unlocking of a differential means are performed by actuating a fork connected to an actuator driven by the electric motor.
Japanese Laid-open Patent Publication No. 324719/2005 discloses a driving device for actuating a fork that connects and disconnects or that performs locking and unlocking of the operating device. In this system, the driving shaft engaged by the operating device for actuating the fork, is projected from a sub case (containing case). In addition the sub case, which forms a case for the driving means, is sealed and structured so that the driving force of the motor can be transmitted to the operational means via the driving shaft by engaging the operational means with an end of the driving shaft projected from the sub case.